Electrical connections have, until recently, largely depended upon traditional methods such as soldering and crimping to effect connection of, for example, conductors and cable shields. In simple applications both of these traditional methods are quite satisfactory. However, these methods are basically permanent in nature. In view of these methods, it remains highly desirable to have a connection of like integrity but which is removable and reusable.
Reusable connectors using a driver member made from a heat-recoverable metal capable of reversing between a martensitic state and an austenitic state have been developed. Such devices are disclosed in commonly assigned U.S. Pat. No. 4,022,519 ("'519"), U.S. Pat. No. 3,861,030 ("'030") and U.S. Pat. No. 3,740,839 ("'839") all of which are incorporated herein by reference. The history of these connectors is generally set forth in '519.
The above-mentioned connectors all have in common an inner socket insert which is shaped generally in the form of a tuning fork having a pair of tines. The tines of '030 and '839 are spring biased to expand a surrounding solid driver of heat-recoverable metal when the metal is in its martensitic site. As will be explained in more detail later, the outward force exerted by the tines on the driver is dependent, among other things, upon the length of the tines. The result is a device which exerts high force but is tine-length dependent. The significance of tine-length dependency will be discussed later with reference to FIG. 8 of the drawing.
Another device utilizing heat-recoverable metal is disclosed in commonly assigned U.S. Pat. No. 3,913,444 ('444), which is incorporated herein by reference. The device of '444 utilizes a split driver of heat-recoverable metal surrounding a socket insert composed of a springlike material having sufficient strength to move the driver when the driver is in its martensitic state. The device of '444 is formed by taking split cylinders of each material and force fitting the two together. While '444 is somewhat more compact than the previously discussed devices, the connecting force generated by the device is comparatively low due to the split driver which depends upon recovery in bending versus the recovery due to hoop forces generated by a continuous or solid driver. Consequently, large contact forces cannot be applied to the substrate by the split driver of '444. The result is a device which exerts low force but is not tine-length dependent.
Yet another connector utilizing heat-recoverable metal is disclosed in commonly assigned patent application Ser. No. 328,161 ('161), filed Dec. 7, 1981, which is incorporated herein by reference. This connector also utilizes a socket insert in the form of a tuning fork having tines similar to the devices disclosed in '030 and '839 discussed earlier. The tines of '161 coact with a split driver of heat-recoverable metal in the form of cantilevered arms to produce a connector having a large range of movement but which like the device of '444, generates low force and which like '519, '030 and '839, is dependent upon the length of the tines.
The instant invention utilizes a solid heat-recoverable metal driver and a split ring socket insert to produce a device which generates high force but is not tine-length dependent. The result is a device which generates the high force of the tine-length dependent devices utilizing solid drivers but is so compact that the socket insert may be wholely contained within the driver.